SmogRank / United States / Wisconsin / Altoona
Altoona, month by month
Altoona has a measured daily mean on 1,288 days since 1 January 2023. Its worst month was June 2023, at 82 US AQI (25.5 µg/m³), 168th of 1,603 cities on that month's world ranking. Its cleanest was April 2024, at 22 US AQI (4.0 µg/m³). 2025 averaged 49 US AQI (8.8 µg/m³), against 36 US AQI (6.4 µg/m³) in 2024.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
3 months
| Month | Why |
|---|---|
| Nov 2025 | 14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| Feb 2023 | 3 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Altoona's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 8225.5 µg/m³ | 168thof 1,603 | Eastern United States and Canada, June and July 2023 United States and Canada, June 2023and 1 more |
| July 2026 | 7321.1 µg/m³ | 293rdof 2,784 | Northern United States and Canada, July 2026 |
| July 2025 | 6818.2 µg/m³ | 248thof 2,889 | North-eastern United States and Canada, 29 July to 9 August 2025 North-eastern United States and Canada, 24 to 28 July 2025and 2 more |
| June 2025 | 6214.8 µg/m³ | 465thof 2,508 | Northern United States and Canada, June 2025 Northern United States and Canada, May and June 2025 |
| August 2025 | 6013.8 µg/m³ | 452ndof 2,901 | North-eastern United States and Canada, 29 July to 9 August 2025 |
| July 2023 | 5712.3 µg/m³ | 365thof 1,432 | Northern United States and Canada, July 2023 United States and Canada, July 2023and 1 more |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Altoona's worst days
Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Altoona, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/altoona-wisconsin/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Altoona now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 19:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).